Research On Confining Head Limit Of Mining Under High Pressurein The Six Coal Mine Of Hebi Coal Mine Based On GIS And Flac^3D

Mining of Permian Shanxi NO2₁ Coal in all mines in Hebi Mining Area,Henan Province,coalbed floor Carboniferous Taiyuan Formation limestone and Ordovician limestone karst water are the main water sources affecting safe production,Ordovician limestone water inrush flooding occurred many times.At present,each mine has entered deep coal mining,The water pressure acting on the bottom of the coal seam is 5.5-6.5 MPa,The lowest mining location in the future will be as high as 9-10 MPa,Ordovician limestone water inrush danger increased.Therefore,Pre-grouting reinforcement technology for coal seam floor in mining face with pressurized mining face,Urgent need for zoning to assess the risk of water inrush from confined water,And determine the limit value of the pressure head.This paper takes the Hebi NO.6 mine as the research object,based on detailed analysis of mine geology,hydrogeological conditions and water filling conditions,Divided NO.6 coal mine hydrogeological type.Analysis of the case of water inrush from the limestone in the historical floor,among the many factors that affect the water inrush from the floor,determined that the water pressure of the Austrian ash,the water-rich ash,the thickness of the effective aquifer of the coal seam floor and the degree of fault development are the main controlling factors affecting the water inrush from the floor of NO.6 mines.Based on international advanced FLAC^3D software,based on the test results of rock physical and mechanical parameters of coal seam and coal seam roof and floor,simulated respectively the bottom plate damage depth after the mining of the six coal seams with the elevation of-460m and-760m.Using fuzzy analytic hierarchy process,the weights of the ash water pressure,the ash-rich water,the thickness of the effective water-repellent layer of the coal seam floor,and the degree of fault development were determined to be 0.249,0.134,0.267,and 0.35,respectively.Using ArcGIS as the platform,the thematic partition map and normalized map of the main control factors are determined,established according to the overlapping and coupling of weights a mathematical model for evaluating the risk of water inrush from the limestone floor of the coal seam of NO.6 Coal Mine Comprehensive evaluation results of comprehensive water inrush coefficient and water inrush risk,dividing the deep planned mining area of the Sixth Mine into a safe area and a water inrush threat zone.NO.6 mines with a coal standard height of-500m and-760m working face,under the condition of oblique length of 120-160m,the floor destructive depth is 17-23m,the thickness of the effective water-repellent layer after deducting the depth of damage of the bottom plate is only 114-162m.According to the calculation of the Austrian ash water level+128m in Hebi mining area,the lower limit of safe mining of No2₁ coal in the six mines is-442m,and the confined water head limit for safe production is 684m.In the future,the coal seam elevation should be advanced pre-exploration in the mining face below-442m,and the comprehensive prevention and control measures for the pre-grouting of the floor in the structural damage area.